1. Field of Invention
The present invention relates to an insulated gate bipolar transistor (IGBT) and a manufacturing method thereof; particularly, it relates to such IGBT which includes a gallium nitride (GaN) substrate and manufacturing method thereof.
2. Description of Related Art
FIG. 1 shows a cross-section view of a prior art insulated gate bipolar transistor (IGBT) 100. As shown in FIG. 1, the IGBT 100 is formed in a silicon substrate or a silicon carbide substrate. The IGBT 100 includes a P-type anode 11, an N-type region 12, a P-type region 13, an N-type cathode 14, a gate 15, and an N-type buffer region 16. The IGBT 100 is a vertical double diffusion metal oxide semiconductor (DMOS) IGBT, which includes a vertical DMOS device and a bipolar junction transistor (BJT). The vertical DMOS device includes the gate 15, the N-type buffer layer 16 as a drain, the N-type region 12 as a drift region, the P-type region 13 as a well, and the N-type cathode 14 as a source. On the other hand, the BJT includes the P-type region 13 as an emitter, the N-type buffer layer 16 as a base, and the P-type anode as a collector. During operation of the IGBT 100, the vertical DMOS device controls the BJT whereby fast switching the high power device BJT.
As shown in FIG. 1, when the IGBT 100 operates, the N-type cathodes 14 and the P-type regions 13 at two sides of the gate 15 form a parasitic junction field effect transistor (JFET). The depletion regions formed by the N-type cathodes 14 and the P-type regions 13 limit the conductive current, deteriorating the performance of the IGBT 100.
Therefore, to overcome the drawbacks in the prior art, the present invention proposes an IGBT and a manufacturing method thereof, to improve the operation speed and reduce the conduction resistance.